Marriage should only be between a man and a woman according to the bible. That trumps anything demanded by 2% of the population, in my opinion.
People have all sorts of religious beliefs, and that's fine. For example, among Catholics, divorce isn't allowed, and what others would call a "second marriage" that includes a divorcee is therefore void and merely a kind of state-sanctioned adultery. That's fine for Catholics, but they ought not to use the law to try to impose their religious taboo on those who don't share their faith. Similarly, if your religion forbids marriage to people of other religions, or to people born outside your caste, or without the permission of the head of your clan or family, or to a woman older than yourself, etc., that's fine for you, but that should be enforced by your church, through instruction, against your co-religionists, not by the state, through force of law, against those who don't share your faith.
Anyway, just because something's in the Bible doesn't mean it should be the basis of law. The Bible, for example, forbids anyone doing any work from sundown on Friday to sundown on Saturday. It forbids women wearing braids in their hair. It forbids tattoos. It forbids wearing garments made of different fibers (e.g., a cotton/polyester blend). It requires that all debts be forgiven in the year of jubilee. It requires that farmers leave the corners of their fields fallow and that they let the poor take any fallen fruit. It forbids eating any shellfish. It requires a host of burnt offerings and other archaic religious rituals. Why ignore all those instructions, but insist on the one about marriage?
